Flashcards in Perinatal Adaptation Deck (22)
What are some placental functions?
Nutrient transport to fetus
Waste product transport from fetus
Acid base balance
Transport of IgG
What are the 3 fetal shunts?
How does the fetus prepare for birth in the 3T?
Accumulation of glycogen-liver, muscle, heart
Accumulation of brown fat- between scapulae and around internal organs
Accumulation of subcut fat
Swallowing amniotic fluid
How does the fetus prepare for birth during labour and delivery?
Onset of labour- increased catecholamines/cortisol
Synthesis of lung fluid stops
In vaginal delivery- squeezes lungs
What circulatory transition occurs at birth?
Pulmonary vascular resistance drops
Systemic vascular resistance rises
Oxygen tension rises
Circulating prostaglandins drop
Foramen ovale closes
What happens to the foramen ovale after birth?
Closes or persists as PFO (10%)
What happens to the ductus arteriosus after birth?
Becomes ligamentum arteriosus
Persistent ductus arteriosus (causing persistent pulmonary HT)
What happens to the ductus venosus after birth?
Becomes ligamentum teres
How is PPHN managed?
By what methods does heat loss occur?
How is a baby adapted for thermoregulation?
Wet when born
What is the main source of heat production in the newborn?
Non shivering thermogenesis- heat produced by breakdown of stored brown adipose tissue in response to catecholamines, not efficient in first 12 hours
What other methods of thermoregulation exist in the newborn?
Babies need help to maintain temp
Why may small for dates/PT babies suffer from hypothermia?
Low stores of brown fat
Little subcut fat
How can hypothermia be avoided in the newborn?
Skin to skin
Describe glucose homeostasis in the newborn
Interruption of glucose supply from placenta
Very little oral intake of milk
Drop in insulin, increase in glycogen
Mobilisation of hepatic glycogen stores for gluconeogenesis
Ability to use ketones as brain fuel
How does hypoglycaemia occur in the newborn?
Increased energy demands-unwell, hypothermia
Low glycogen stores- small, premature
Inappropriate insulin/glucagon ratio- maternal diabetes, hyperinsulinism
What happens to fetal haemoglobin in the newborn?
Increase in 2,3 DPG shifts curve to right
Where does haematopoiesis move to in the newborn?
What can result from adult Hb being synthesised more slowly than fetal Hb breakdown?
Nadir at 8-10 wks
Why does physiological jaundice occur in the newborn?
Breakdown of fetal haemoglobin
Conjugating pathways immature
Rise in circulating unconjugated bilirubin
Generally not harmful unless very high levels